Sleep apnea in morbidly obese patients: prevalence and clinical predictivity.
BACKGROUND
Little is known about the prevalence of obstructive sleep apnea-hypopnea syndrome (OSAHS) in morbidly obese patients and whether such patients show peculiar clinical findings that may make it easier to suspect and diagnose OSAHS.


OBJECTIVE
To investigate prevalence of OSAHS in patients with morbid obesity and find a simple structured model for predicting the results of polysomnography.


METHODS
The study enrolled a group of 101 consecutive inpatients (33 males, age range 20-80 years) with a body mass index > or =40, whose symptoms of OSAHS were not known, and a validation group of 45 patients.


RESULTS
Habitual snoring, nocturnal apneas or awakening as well as diurnal sleepiness were frequent findings (90.1, 40.6, 50.5 and 61.4%, respectively). Chronic obstructive pulmonary disease, hypertension, diabetes and myocardial ischemia were also frequently associated (22.8, 56.4, 30.7 and 6.9%, respectively). OSAHS was found in 61 (60.4%) patients, in 33.7% it was of severe degree. A multivariate logistic regression model allowed to select the independent predictors of OSAHS: age, male sex, diurnal sleepiness and the value of minimum nocturnal saturation. Sensitivity of 97%, specificity of 77% as well as positive and negative predictive values of 87% and 95%, respectively, were obtained; similar results were found in the validation group. When the best obtainable cutoff on the receiver operating characteristic curve is below 40%, the instrumental diagnosis might be excluded in as many as 33% of cases, since they are not affected by OSAHS or have OSAHS of mild degree.


CONCLUSIONS
OSAHS is present in almost two thirds of morbidly obese patients. By applying the prediction model we propose, one may calculate the probability of a morbidly obese patient of being affected by OSAHS.
Palla
Antonio
A
Cardiac and Thoracic Department, Section of Respiratory Disease, University and Hospital of Pisa, IT-56124 Pisa, Italy. a.palla@med.unipi.it
Digiorgio
Michela
M
Carpenè
Nicoletta
N
Rossi
Giuseppe
G
D'Amico
Ilaria
I
Santini
Ferruccio
F
Pinchera
Aldo
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009767:Obesity, Morbid / Q000150:complications*; D011237:Predictive Value of Tests; D015995:Prevalence; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology / Q000209:etiology*; D055815:Young Adult